The mechanism of adventive embryogenesis was studied at ultrastructural level. Three Citrus cultivars were used as material, two poly-embryonic and one mono-embryonic. The adventive embryos in Citrus are initiated in the nucellar tissue adjacent to the embryo sac in the micropylar half and incidentally from the chalazal end. The nucellar embryoids derive from initial cells. Initial cells are present already at the time of flowering in the poly-embryonic cultivars: in the mono-embryonic cultivar initial cells are absent. At the mature embryo sac stage the initial cells have a « meristematic » character. Before division they develop new cell walls and become « zygote-resembling » cells. During this development they are isolated and their original cell walls are disintegrated. Simultaneously the surrounding nucellar cells degenerate and disappear and the initial cells become embedded in the endosperm.
Karyotypes of three barbels belonging to the group of «small» African species of Barbus sensu lato, B. bigornei, B. ablabes and B. macrops from the Republic of Guinea (Western Africa), were investigated. Diploid chromosome (2n) and chromosome arm (NF) numbers were for B. bigornei 2n = 48 and NF = 96, for B. ablabes 2n= 50 and NF = 98, and for B. macrops 2n = 50 and NF = 92, respectively. The first pair of metacentric chromosomes in all karyotypes was remarkably larger, and it can be considered as a «marker» element for these 3 species. The karyotype characteristics of Barbus species under study demonstrate that they belong to the diploid group of African barbels and they are, in fact, not related to the genus Barbus sensu stricto which is of a distinct evolutionary polyploid origin. Karyology of this poorly studied African cyprinid group is reviewed and discussed.
In contrast to the enormous variability of Neotropical fish species, genetic information about many groups is not yet available. Chromosomal studies have greatly contributed to the characterization of several species, providing important data on these animals. We performed the first cytogenetic characterization of the Amazonian fish species Brachyplatystoma filamentosum (Pimelodidae), popularly known as “piraíba”. The results revealed a diploid number of 2n = 56 composed of 24 metacentric, 12 submetacentric, and 10 acrocentric chromosomes in both females and males. After silver nitrate treatment (AgNORs) it was possible to visualize the nucleolus organizer region located in the terminal portion of the short arms of subtelocentric chromosome pair 22, presenting size polymorphism. Hybridization with 18S and 5S rDNA probes confirmed the number and location of 18S marks rDNA in pair 22 and differences in the size of signals among homologs. The 5S rDNA genes were localized near the centromere on the short arms of chromosome pair 19. Constitutive heterochromatin (C-bands) were localized predominantly in the terminal regions of the chromosomes, and also occurred in some interstitial and centromeric positions. The chromosomal genetic data obtained in this study contribute to the biological characterization of B. filamentosum, which has economic and ecological importance as the largest freshwater catfish occurring in many rivers of the Amazon and Tocantins-Araguaia basins in Brazil. These results may also be used in to infer relationships among Pimelodidae species.
The somatic chromosome numbers and detailed morphometric properties of eight of the nine annual Turkish Carduus L. taxa were examined. The somatic chromosome numbers were 2n = 2x = 22 in C. rechingerianus Kazmi; 2n = 2x = 28 in C. argentatus L., C. acicularis Bertol. and C. pycnocephalus L. subsp. albidus (M. Bieb.) Kazmi; 2n = 2x = 34 in C. pycnocephalus subsp. arabicus (Jacq. ex Murray) Nyman and subsp. breviphyllarius P. H. Davis; 2n = 2x = 50 in C. nervosus K. Koch.; and 2n = 2x = 62 in C. pycnocephalus subsp. pycnocephalus. Karyotype analysis indicated that chromosomes of the Carduus taxa generally have centromere median region (m), submedian region (sm), and rarely median point (M) of the chromosome. A pair of satellite chromosomes (sat-chromosome) was observed in C. pycnocephalus subsp. breviphyllarius. The findings for each of the analysed taxa are compared with the results of previous studies. The chromosome number and morphology of C. nervosus, C. rechingerianus, C. argentatus, C. pycnocephalus subsp. arabicus and subsp. breviphyllarius are newly reported here.
Karyotypes and meiosis of five spider species belonging to the families Gnaphosidae, Miturgidae and Philodromidae were studied using standard Giemsa staining. The male diploid chromosome numbers (2n) and the sex chromosome systems were as follows: Drassodes lutescens: 2n = 21 (X0), Micaria albovittata: 2n = 22 (X1X20), Cheiracanthium mildei: 2n = 26 (X1X20), Cheiracanthium pennyi: 2n = 26 (X1X20) and Philodromus lividus: 2n = 28 (X1X20). Chromosomes of all specimens were telocentric. During the first meiotic division, 10, 10, 12, 12 and 13 autosomal bivalents, respectively, and two sex chromosomes were obtained, with the exception of Drassodes lutescens, which had a different type of sex chromosome system (♂X0/♀XX). During the second meiotic division, two types of nuclei were determined, with or without the sex chromosomes. These karyological data are useful for a better understanding of the chromosomal evolution of araneomorph spiders.
The Callichthyinae subfamily is composed of five genera with a small number of described species. Molecular cytogenetics studies show the scarcity of records for this subfamily. The aim of the present study was to employ cytogenetic parameters in the analysis of three species belonging to the subfamily Callichthyinae sampled from the Paraná River (Brazil). Callichthys callichthys had 2n = 56 chromosomes (26 m-sm + 30 st-a); Lepthoplosternum pectorale had 2n = 64 chromosomes (8 m-sm + 56 st-a); and Hoplosternum littorale had 2n = 60 chromosomes (8 m-sm + 52 st-a). Regarding the location of the nucleolar organizer regions (NORs) (Ag-staining and 18S rDNA-FISH), different situations were found: single NORs in H. littorale and C. callichthys; multiple NORs in L. pectorale, with intra-individual and inter-individual variation. Heterochromatin was observed in the centromeric region in the chromosomes of the three species. Equilocal, interstitial bands were also found in H. littorale. Physical mapping of 5S ribosomal genes by FISH shows eight 5S rDNA sites in C. callichthys; four 5S rDNA sites in H. littorale and six 5S rDNA sites in L. pectorale. Using cytogenetic markers (diploid number, chromosome formula, NORs, heterochromatin distribution pattern and 5S and 18S rDNA sites), the chromosomal evolution in Callichthyinae is presented: callichthys shows mostly basal chromosomal conditions, with mostly derived chromosomal conditions verified for the Hoplosternum–Dianema clade and Megalechis–Lepthoplosternum clade.
Asparagus officinalis L. is a dioecious plant. A region called the M-locus located on a pair of homomorphic L5 chromosomes controls sexual dimorphism in asparagus. This study aims to conduct microdissection and DOP-PCR on the L5 chromosome, and then physically locate the DOP-PCR products of the L5 single chromosome on the metaphase chromosome of asparagus by chromosome painting. The micromanipulator results indicated that the L5 chromosome was successfully microdissected and its DNA was amplified by DOP-PCR. The molecular weight of its PCR products ranged from 250 to 3000 bp according to 1% agarose gel electrophoresis. The second round DOP-PCR products of the L5 chromosome were labeled with Alexa Fluor-488 by using the nick translation method and the metaphase chromosomes of male asparagus were painted, showing that the fluorescence signals were distributed on the centromeres and secondary constriction areas of all chromosomes. This study has provided a basis for the construction of L5 chromosome DNA library, which will facilitate specific probe screening, molecular mapping, gene cloning, and DNA sequencing for this chromosome.
Cytogenetic studies were carried out in three species from genus Astyanax: Astyanax paranae (Tagaçaba Stream and Tauá Stream), Astyanax altiparanae (Iguaçu River and Maringá Stream) and Astyanax fasciatus (Maringá Stream). Both populations of A. paranae featured 2n = 50 chromosomes, although with different karyotype formulae and Ag-nucleolar organizer regions systems. Using the FISH technique in the Tagaçaba population, it was possible to detect rDNA genes in 14 chromosomes and bitelomeric marking in one chromosome. The constitutive heterochromatin pattern also showed differences between the two populations. Moreover, the Tagaçaba population showed macrochromosome B in 50% of analyzed females. Both A. altiparanae populations featured 2n = 50 chromosomes, but also differed in karyotype formula. Both populations featured multiple-NOR systems and quite similar constitutive heterochromatin patterns. For the A. fasciatus population from Maringá Stream, the diploid number was 2n = 46 chromosomes with karyotype formulae 14m, 10sm, 12st and 10a (fundamental number = 82), with single-NOR system and heterochromatin pattern showing evident markers in the telomeric regions of several subtelocentric and acrocentric chromosomes. The data presented for this species differ from some previously analyzed populations with regard to diploid number (2n = 48 chromosomes) and karyotype formula for those with the same diploid number. The present data strengthen the accentuated cytogenetical variability of the genus Astyanax.
This study presents results of histopathologic, cytogenetics and flow cytometry analyses performed on Macoma balthica collected from the Gulf of Gdansk (Baltic Sea) in 2003 in order to compare the techniques for diagnosis of neoplasia. The proportion of affected clams gave a crude prevalence of 15.7 %. The four stages of the disease defined by histology and three stages of neoplasia defined by flow cytometry were reported. Stage I defined by flow cytometry corresponded to stages I and II defined by histology. Chromosome analysis did not lead to a staging of neoplastic progression. Both cytogenetics and flow cytometry indicated a difference in the DNA content of non-neoplastic and neoplastic cells. Cytogenetics examination marked that the range of chromosome numbers scored in abnormal mitosis corresponded to pentaploid-like cells (2.37 x diploid) and was similar to the mean DNA quantity identified using flow cytometry (2.36 x diploid). These methods generally have lower diagnosis sensitivity because with both techniques only a part of an animal can be studied. Thus, histology examination appeared to be the most sensitive tool for detection of the possible foci of neoplastic cells, metastasis and rare tumour cells freely circulating in the hemolymph in the early stages of the disease. Cytogenetic analysis has been considered as an important tool for the evaluation of aquatic environment quality as well as for the ecological risk assessment. Flow cytometry provided a rapid and easy method for discrimination of the aneuploid cells within thousands of cells per individual. Thus, in diagnosis of early stages of the cancer as well as early metastasis histology analyses should be performed. Chromosomes analysis and flow cytometry examination are important techniques for detection abnormalities in cell division, cell viability and DNA quantity. They appear to be very important in diagnosis of tumors based on high aneuploidy level.
Chromosomes of the short-tailed shrew Blarina brevicauda, which display the numerical polymorphism arisen from Robertsonian rearrangements, were analyzed with conventional and silver staining and G- and C-banding techniques. With respect to all specimens examined in the present study, the diploid chromosome number (2n) and fundamental autosomal arm number (FN) were 50 and 48, respectively. The karyotype consisted of 24 pairs of acrocentric autosomes, a large-sized metacentric X chromosome, and a small-sized submetacentric Y chromosome. The comparison with previous findings suggested the geographic polymorphism of Y chromosome in this species. All autosomes and the X chromosome carried slight centromeric constitutive heterochromatin, whereas the Y chromosome was entirely heterochromatic. On the satellites of short arms of two autosomal pairs, the nucleolus organizer regions (NORs) were recognized. The G- and C-banded and Ag-NOR-stained karyotypes presented in the present study could be useful cytogenetic characteristics for specification of chromosomes participating in Robertsonian rearrangements within this species and for karyo-systematic study of genus Blarina.
C-banding patterns were analyzed in six taxa of Paris: P. polyphylla var. chinensis, P. marmorata, P. luquanensis, P. thibetica, P. polyphylla var. yunnanensis and P. polyphylla var. alba. All plants had a diploid chromosome number of 10. The basic banding consisted of three metacentric and two teloblastic chromosomes. All taxa showed interspecific variation in karyotype structure. P. thibetica had a unique C-banding pattern, having six bands on the long arm of the middle median centromeric chromosomes. P. polyphylla var. yunnanensis had mostly faint C-bands. Chromosome morphology and C-banding patterns have been used for chromosome identification and population divergence detection.
Common rust of the coffee-shrub (Coffea sp.): study of the fungus « Hemileia vastatrix » Berk, et Br. in leaf-tissues. After the germ filaments of uredospores of Hemileia vastatrix penetrated by way of stomata, we have studied the development of the intercellular mycelium of this fungus, its localization in the mesophyll, its branches and its walled and dicaryotic structure. We have described the relations between hyphae and leaf-cells of the coffee-shrub such as rounding and close contact between the walls of both organisms which is sometimes maintained over long distances, emission of short and pointed oranches which go through the wall and formation of « internal appressorium ». We have studied the first developmental stages of a haustorium, while stressing the modifications suffered by the walls of both organisms and we have observed the differentiation of the protective coverings of the maturing haustorium such as the collar, the encapsulation, the extra-haustorial membrane and the sheath. We have studied the distribution of the haustoria in the mesophyll, their localization in relation to the host cell and their mother cell. We have observed the differentiation of intercellular hyphae into fruiting hyphae producing uredospores and their clustered discharge through stomata.
The fine structure of the haustorium of the pycnio-aecial stage of Melampsora pinitorqua in infected cells of cotyledons of Pinus pinea was studied. Some features were found to be different from those of the uredial-telial stage of the same rust on Populus tremula. The mother cell wall lacked thichening at the penetration site; the penetration site was found to be very wide; the mother cell wall was continuous with the haustorial wall and the fungal wall was clearly distinct from the host wall; the haustorium had a hypha-like shape and a septum in its proximal region. The interface between the haustorium and the host cell, and the relationship of some host organelles with the haustorium appeared similar to those of the uredial-telial stage of Melampsora pinitorqua on aspen.
Karyotypes of Sorex caecutiens from Cheju Island of Korea were examined with conventional staining and G-banding by trypsin treatment stained with Giemsa (GTG). The diploid and fundamental autosomal arm numbers were 42 and 66, respectively. The autosomal complement in the karyotype comprised six pairs of metacentrics, seven pairs of submetacentrics or subtelocentrics, and seven pairs of acrocentrics. The X was a largest acrocentric chromosome, and the Y was a small subtelocentric chromosome. Chromosomal constitutions and G-banding pattern of S. caecutiens from Cheju Island were essentially identical to those reported for S. shinto from Honshu Island, Japan. This similarity may indicate the ancestral character of the monophyletic S. caecutiens/shinto group.
Karyomorphological analysis of four species of Schoenoplectus (Cyperaceae) from north-central Mexico were carried out. Chromosome numbers ranged from 2n = 38 to 2n = 84. New records of counting are given for Schoenoplectus acutus var. occidentalis (2n = 38 and 2n = 84) and S. americanus (2n = 66). Intra-individual variation in chromosome number is reported for the first time for S. acutus, with a rare polyploid mixoploidy with a prevalence of cells with 2n = 38 (36 small + 2 compound, larger chromosomes) and a few cells with 2n = 84 small, dot-shaped chromosomes, this being the first record of polyploid mixoploidy for Cyperaceae. Mean length of the diploid set ranged from 51.5 μm (S. tabernaemontani) to 79.5 μm (S. acutus). The lowest average chromosome length for the dot-shaped chromosomes was 0.69 μm (S. acutus) and the highest 1.62 μm (S. tabernaemontani); the pair of large chromosomes in S. acutus reached 3.17 μm. A low interchromosomal asymmetry index (A2), 0.11 to 0.14 was found, very similar among all the species except for S. acutus (A2 = 0.30). Absence of primary constrictions was confirmed. The most common mechanism of karyotype variation in the studied species is dysploidy, followed by polyploidy. A comparison of chromosome numbers between Schoenoplectus and the recently segregated Schoenoplectiella based on the literature reveals that Schoenoplectus has higher numbers (n = 18 to 64; 2n = 36 to 84) than Schoenoplectiella (n = 5 to 44; 2n = 18 to 76) as well as a higher prevalence of disploids.
The chromosome morphology of four populations of Dugesia gonoce-phala s.l. from various European localities is described. Three populations (S1, V26 and V35) showed diploid complements of 16 metacentric chromosomes, whereas one population (V28) has a triploid complement of 24 meta- and submetacentric chromosomes. The karyotypes of the populations show small variation of chromosome length and centromere position, which do not enable the identification of individual chromosomes. For a statistical approach of this problem, the 95% confidence limits of relative length and centromeric index were calculated for each chromosome and set out in two dimensional scatter diagram. It is argued that in cases where chromosomes decrease gradually in relative length and show similar centromeric indices, matching of chromosomes in pairs is statistically unsound. Chromosome differentiation techniques were introduced to obtain characteristic banding patterns for chromosome recognition. Tentative results obtained with the BSG-technique showed clear C-bands at the telomeres and centromere regions of some chromosomes. Silver (Ag-As) staining demonstrated the presence of Ag-NORs in two chromosomes of one of the populations. Quinacrine staining of squashed blastemas revealed rather uniform fluorescence intensity at all chromosomes.
Somatic chromosome numbers and karyotype of Hippocrepis unisiliquosa ssp. unisiliquosa L. and Hippocrepis ciliata L. (Leguminosae) collected from Turkey were examined. Chromosome numbers were determined as 2n = 2x = 14 in Hippocrepis unisiliquosa ssp. unisiliquosa L. and Hippocrepis ciliata. The mitotic chromosome number and karyotype of the taxa were reported here for the first time.
The generative cell divides into two irregular shaped sperm cells, with a sharp angle between them. A thin space separates the membranes of the two sperm cells from the membrane of the vegetative cell. This space is interrupted by cytoplasmic channels. The sperm cell cytoplasm contains small mitochondria with evident cristae, Golgi bodies with few plated cisternae, many free ribosomes, some vesicles and some small vacuoles. The nuclei at mature stage are multilobate and have many pores. Plastids are not present. At the sides of the pores the intine consists of an electrondense layer of compact fibrils. In the vegetative cytoplasm two types of RER are present. Around the vegetative nucleus and the sperm cells the cisternae are long. Short and sacculated cisternae surround the plastids. In the early stages of development also short RER cisternae surround the drops of lipid. At anthesis lipids are absent.
Endopolyploidy is a common feature in seed plants. This phenomenon occurs during early development. Flow cytometry of 54 individuals of the species Trifolium pratense variety Manuela, in the vegetative organs during four ontogenetic stages is described. Fresh plant material grown from seeds was used for the analysis. The calculation made on the basis of the mean cycle value revealed that the level of endopolyploidy is different in various organs during the ontogeny. The highest endopolyploidy was recorded in the cotyledons of the first stage (1.0) and the lowest in the third leaf of the fourth ontogenetic stage (0.18). It was noticed that the degree of endopolyploidy decreased during the ontogeny in most of the plants and thus the ontogenetically oldest organs had higher endopolyploidy than the younger ones.
Teliospores of Melampsora pinitorqua Rostr. were collected in the formation, overwintering and germination stages and observed by transmission electron microscope. Some information about their general ultrastructure is given, particularly concerning the cell wall, lipid bodies, mitochondria, ER, cytoplasmic vesicles, vacuoles, unidentified membrane formations, nucleus and germ tube wall. Some organelle changes occurring from the maturation to germination stage were observed.RIASSUNTOTeleutoconidi di Melampsora pinitorqua Rostr. su foglie di Populus tremula sono stati raccolti in località Luriano (Monticiano, Siena) nei periodi della loro formazione, svernamento e germinabilità, e osservati al microscopio elettronico.Essi presentano: una parete bistratificata non particolarmente complessa, un nucleo cospicuo con nucleolo ben visibile, un caratteristico accumulo di globuli lipidici, numerosi mitocondri, diversi piccoli vacuoli. Nel periodo di germinabilità si rendono evidenti anche i ribosomi, cisterne di ER e vescicole citoplasmatiche. La parete del tubetto germinativo appare formarsi come uno strato exnovo interno alla parete del teleutoconidio. I teleutoconidi fissati nel periodo di germinabilità rispetto a quelli svernanti mostrano: una minore quantità di globuli lipidici; un aumento del contenuto citoplasmatico in generale accompagnato dall'evidenziazione delle membrane quali il plasmalemma, ER, membrana nucleare, membrana limitante i mitocondri, dall'aumento del numero dei vacuoli e dalla comparsa di vescicole citoplasmatiche.
3-[(1-methyl-4-nitro-1H-imidazol-5-yl)thio]-4-methyl-1,2,4-triazole (MNITMT) is an immunosuppressive agent used to treat autoimmune disorders. The objectives of this study were to determine the genotoxic and cytotoxic effects of MNITMT on bone marrow cells of mice. Various concentrations of MNITMT were tested (2, 5, 10 and 20 mg ml–1). Bone marrow cells were prepared for mitotic and mitodepressive indices and blood smears for micronuclei. Cell viability of cultured bone marrow cells was determined using an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide)] assay and the proliferation index was calculated. Our results show that MNITMT significantly lowered the mitotic index (MI) at the highest two doses (10 and 20 mg ml–1) with 14.3 % and 14.9 % at 24 h, 19.2 % and 19.6 % at 48 h, 15.4 % and 19.8 % at 72 h, respectively as compared to control. The percentage of micronuclei (MN) increased with increasing the MNITMT doses 2, 5, 10 and 20 mg ml–1 (79, 125, 141 and 145% respectively). Administration of 2, 5 and 10 mg ml–1 of MNITMT did not cause any bone marrow toxicity, while approximately 50% reduction in the rate of proliferation was observed using the highest dose, 20 mg ml–1. These results suggest that high doses of MNITMT cause both genotoxic and cytotoxic effects.
Cytological features and karyomorphology of two endemic giant pill-millipedes (Arthrosphaera fumosa and A. magna) of the Western Ghats were studied based on the meiotic cell divisions using Giemsa staining technique. Different meiotic stages of spermatogonial cell divisions were compared and karyotypes were constructed from the metaphase stages. The diploid chromosome number, 2n = 30, in A. fumosa as well as A. magna with XY sex determination system was seen. Most of the meiotic chromosome behaviors were similar between the millipede species. All meiotic chromosomes in A. fumosa belonged to acrocentric type, while in A. magna 27 were acrocentrics, two (3rd and 10th) were sub-metacentrics and one (5th) was metacentric. The relative lengths of autosomes in A. fumosa and A. magna were 21.9–109.3 and 38.8–90.6, respectively. The X chromosome was longer than the Y chromosome in both millipedes. The relative lengths of the X chromosomes of A. fumosa and A. magna were 130.1 and 103.6, while for the Y chromosome they were 113.6 and 92.6, respectively. Based on this study and earlier cytological and karyological studies on Arthrosphaera, the diploid chromosome number has been predicted to be higher than 30. Further assessment is needed of identified and unidentified species distributed in the Western Ghats of India and other geographic locations to follow the chromosomal evolutionary pattern.
Keywords: Arthrosphaera; chromosomes; Diplopoda; karyotype; giant pill-millipedes; spermatogonial meiosis; Western Ghats
In this study, 15 different accessions of Iranian lettuce cultivars and varieties that were collected from different regions were investigated. Starting from the root apical meristem, we measured the number and size of the chromosomes. The karyotypic formula was determined. The basic chromosome number was n = 9 in all accessions, possibly due to ancient origin, also all accessions had morphological dissimilarity, and heteromorphisms between chromosomes and their chromosomal types were metacentric, submetacentric and subtelocentric. Analysis of variance showed significant differences between chromosomal characteristics. The maximum size of the estimated genome (in terms of chromosome length) was that of the Qom accession (62.45 μm). The minimum size was that of the Babol accession (19.94 μm). Symmetrical and asymmetrical karyotypes were observed between the accessions. The formula of the Ahwaz accession was 12m + 4sm + 2t with the maximum centromic index (40.93%), while the Fasa accession had a 4m + 10sm + 4st karyotypic formula and the minimum value (28.73). There were different numbers of satellites present on the chromosomes in the different accessions. Some of them had two satellites, some one and the others none. In principle component analysis two components had more than 82.75% of the data variations. Based on the first and second components the accessions separated into three groups. Cluster analysis of karyotypic traits based on the unweighted paired group method using arithmetic average (UPGMA) separated the accessions in three groups. The results of this study will be useful for accession classification and identification.
The chromosome number and morphology in six species of the sections Babounya (DC.) O. Hoffm. and Achillea of the genus Achillea L. (Asteraceae) were investigated using karyological techniques. Sample plants and seeds of A. santolinoides Lag. subsp. wilhelmsii (K. Koch.) Greuter, A. falcata L., A. magnifica Hub. - Mor., A. pannonica Scheele, A. crithmifolia Waldst. & Kit. and A. nobilis L. subsp neilreichii (A. Kern.) Formánek were collected from natural habitats in 2005. The chromosome number found in six species was 2n = 18. All chromosomes had median point (M), median region (m), and submedian (sm) centromers. An increase in asymmetry was not observed in the karyotypes of the species studied. None of the studied species had any B chromosomes.
In previous papers it was reported that a Robertsonian translocation (centric fusion) affected external phenotype in the grasshopper Leptysma argentina and that thorax height was the target of adult viability selection. In the present paper two populations of L. argentina at different latitudes, with different centric fusion frequencies, were studied. It was demonstrated that selection acts on roughly the same targets but in opposite directions. In the northernmost population longevity selection acted primarily on thorax height (TH), leading to an increase of that variable. In the southern population, longevity selection leads to an increased femur length (FL) but to a decreased body size (including TH). Longevity selection affects karyotype frequency, leading to an increase of fusion homozygote frequency; however, fusion 3/6 significantly increases FL. This is consistent with an increase in fusion frequency along the season. The fact that longevity selection in one population increases and in another decreases body size is interpreted as an interaction between environment and body size, of the sort already detected in laboratory strains of Drosophila melanogaster.
The additive and epistatic effects and their genotype × environment (GE) effects on percentage gain with physiological traits under different environments were analyzed in soybean. The genetic characters of physiological traits in soybean and characters of quantitative trait loci (QTL) detected in different environments are discussed. A backcross inbred line (BIL) population of soybean derived from the cross of strong drought tolerant wild soybean, “SNWS0048” as a recipient parent and drought-sensitive variety “Jinda73” as a donor parent was examined to identify the QTL and epistatic QTL and GE effects on drought-tolerant physiological traits in Shanxi, China, in 2008 and 2010. Six QTLs with additive (a) effects and/or additive × environment interaction (ae) effects and three pairs of QTLs with additive × epistatic main (aa) and/or epistasis × environment interaction (aae) effects were detected in different water environment over two years. Six QTLs with a effects and/or ae effects were mapped to linkage groups D2, G, M and N. Among them, there were two QTLs without ae effects, one with ae effects in all four environments, two QTLs with ae effects in two environments and one QTL with ae effects in only one environment. Among three pairs of QTLs, one pair was identified with aa effect and aae effect, one pair only exhibited aa effect, and one pair only had aae effect without aa effect. These indicated that different water environments could affect the expression of genes relevant to drought tolerant traits.
Aim: The aim of this study was to investigate the in vitro antioxidant and anticancer activities of diethyl ether, petroleum ether, ethyl acetate, methanol and water (infusion and decoction) extracts from Vitex agnus-castus L. (Verbenaceae) seeds.Materials and methods: Antioxidant activities of crude extracts from V. agnus-castus L. seeds were evaluated by 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) scavenging assay, and anticancer activity of the extracts on MCF-7 breast cancer cells of extracts were evaluated by determining cytotoxic, DNA damaging and apoptotic activities with trypan blue exclusion assay, comet assay and Hoechst 33258/propidium iodide double staining.Results: Although V. agnus-castus L. methanol and water (infusion and decoction) extracts showed significant DPPH scavenging activity, diethyl ether, petroleum ether and ethyl acetate extracts have low DPPH scavenging activity. However, all of the extracts showed a significant cytotoxic, DNA damaging and apoptotic effects in MCF-7 human breast cancer cells. Cytotoxic, DNA damaging and apoptotic activities of the extracts increased in concentration dependent manner.Conclusion: Our results suggest crude extracts of V. agnus-castus seeds have potent antioxidant, cytotoxic and apoptotic activity. Further investigations are required for the isolation and identification of individual phenolic compounds in the extracts.
The onion plant (Allium cepa L.) is a suitable indicator plant for the determination of potential genotoxic agents in the samples taken from the environment. The genotoxic level of the agent under study is reflected by structural changes of the chromosomes and their changed numbers. The chromosomes under study are taken from the meristem cells of the young growing onion roots. A healthy normal onion cell has 16 (2n = 16) chromosomes. They are relatively large and so very appropriate for the detection of morphological changes. Prior to the chromosome study the root tip cells were immersed in a 0.1% aquatic solution of colchicine which stopped the mitotic cycle continuing beyond metaphase. The changes in morphology varied from a single distortion of a single chromosome up to several morphological changes observed on many chromosomes. We identified 15 categories of morphological aberrations which are classified into three groups: chromatid damage (CtD), centromere damage (CmD) and chromosome damage (CsD). CtD includes: single break chromatid, double break chromatid, isochromatid break, multiple break chromatid, gap chromatid, centric ring chromatid, acentric ring chromatid and triradial chromosomes. CmD includes: break centromere, gap centromere, single break centromere, double break centromere and multiple break centromere. CsD includes: ring chromosomes and dicentric chromosomes. Sometimes also the chromosome number changed which occurred as aneuploidy with monosomy 2n = 15 (2n =16 – 1) and euploidy – increased number of the basic chromosome number (2n = 6x – 8x). We identified also the translocation: t(3p–; 5p+).
Silver nanoparticles are one of the most commonly used nanomaterials. However, there remains insufficient information on their genotoxic effects. The goal of this study was to investigate cytotoxic and genotoxic effects of chitosan-coated AgNPs using the well-established Allium test. Root tip cells were treated with solutions at different concentrations (1, 2.5, 5 and 50 mg l−1) of chitosan-coated AgNP (size: 10–30 nm; organic coat: 2–5 nm). On the same slide mitotic abnormalities, chromosome aberrations and micronuclei were detected. Also mitotic and phase indexes were analyzed. No cytotoxic or genotoxic effects were found at concentrations below 5 mg l−1. The absence of induction of chromosomal and mitotic abnormalities by chitosan-capped AgNPs at low concentrations is possibly due to the capping, which may partly protect the cells from direct interaction with the AgNPs. Mitotic and chromosomal abnormalities and micronuclei were detected at a concentration of 50 mg l−1. Significant increase in mitotic index was found at 5 and 50 mg l−1 concentrations of AgNP. The data demonstrated that chitosan-coated AgNP exhibit both clastogenic and aneugenic activity.
The effect of environment contaminants on genome instability and changes in enzyme activity (acetylcholinesterase (AChE), glutathione S-transferase activities (GST), etoxyresorufin O-deethylase (EROD) and metallothionein (MT)) of Chironomus riparius Mg. from Bulgarian and Turkish stations over two years (2009, 2010) as well as laboratory reared larvae were studied. Physicochemical analysis of the sediments from the field stations indicated the presence of heavy metal pollutants (Cr, Cu, Mn, Pb, and Cd) whose concentrations were higher than the reference data. Genome instability was determined by somatic structural and functional alterations of the polytene chromosomes. In the field sites of both countries somatic aberrations occurred at a significantly higher frequency (p C. riparius in sediments with higher concentrations of trace metals (Derincay River, Turkey and Chaya River, Bulgaria), was found to possess a high spectrum of somatic chromosome rearrangements with a somatic index of 2.53 and 3.25 respectively. Changes in functional activity included decreased activity of the Balbiani rings (BRs) and nucleolar organizer (NOR). The observed chromosome alterations agree with the high degree of trace metal pollution and high activity of the studied enzymes. However, no correlation between single somatic chromosome rearrangements and concentrations of specific metal ions was defined. The data are discussed in the light of the wide variety of interactions of metals in nature. The results show that the genome response and biochemical markers are sensitive markers of toxicity and provide early warning indicators of contaminants in the environment.
Amsonia orientalis Decne. (Apocynaceae) is a medically useful and critically endangered plant which has very restricted distribution world-wide. The root tips and flower buds of A. orientalis were used as an experimental material and they were squashed in aceto-orcein. Fresh flowers and a liquid medium were used for pollen germination tests. In spite of the small size of the cells and chromosomes, all phases of mitosis and meiosis were observed. Generally the phases of mitosis were regular but there were a few abnormalities, such as laggard chromosome in metaphase and bridge formation in anaphase. There was a good relationship between the stages of pollen development and floral bud length. As a result of the cytokinesis, tetrahedral types of tetrads were occurred in microsporogenesis. The tetrad nuclei resulting from the simultaneous type of meiosis were found to be of equal size. Pollen germination had started from the first hour and pollen tube lengths and germination percentages regularly increased with increasing time. This is the first study that identifies mitotic and meiotic cycles and pollen germination in A. orientalis. Our findings about the mitosis and reproduction biology of this critically endangered plant will be useful for in vitro and in situ conservation, taxonomic and genetic studies.
The karyomorphology of seven different cultivated varieties of Capsicum annuum L. was studied to determine similarities and differences amongst the karyotypes and to provide diagnostic features of the different chromosomes in the haploid complement of each variety. Capsicum annuum exhibits certain morphological variations with respect to fruit size, fruit stalk length, number of fruits per plant, number of seeds per fruit, etc. Therefore seven morphologically distinct varieties were used for studies. It was observed that although the somatic chromosome number is the same (2n = 24) in all the seven varieties studied, they differed markedly in their chromosome morphology and total haploid chromatin length. The total length of the haploid complement in the varieties studied varied from 48.26 to 62.96 μm. All the varieties have comparable chromosome size, karyotype symmetry and chromosome types. The number of satellites varied from 1 to 2 and they were present at the end of the short arm. Long arm/short arm ratio was the highest in cultivated variety Pusa sadabahar, showing its advanced nature. The total haploid chromatin length was found to have a significant positive correlation with the pericarp weight, number of seeds/fruit, fruit stalk length, fruit girth and fruit surface area. Thus from the karyotype features, the varieties appear to be distinct. The seven cultivated varieties of Capsicum annuum L. have comparable chromosome size, karyotype symmetry and chromosome types. They exhibit close relationships which indicate their probable origin from a common ancestor. In finer details, some recognizable differences were noticed between the varieties. Thus the karyotype analysis of the seven varieties revealed that minute structural alteration of chromosomes associated with genomic chromatin length, etc, has played an important role in establishment of new cultivated varieties.
During microsporogenesis sometimes the chromatin materials migrate from one cell to another by intermeiocyte connections. In the present study, during induction of tetraploidy in sunflower, changes in the normal behaviour of chromosomes was detected. Besides chromosomal aberrations, cytomictic connections were frequently recorded. Cytomixis has been reported by many researchers in many diploid or tetraploid plants. In sunflower, cytomixis in colchiploids has not been recorded. In the current study high numbers of cytoplasmic connections were observed in the plants failing to reach higher ploidy level. Formation of cytoplasmic connections was very high, leading to many hyperploids, hypoploids and even empty pollen mother cells (PMCs). Cytomixis occurred frequently, with two to many meiocytes engaged in exchange of chromatin through one or multiple cytoplasmic connections. Few rare polyploid PMCs with cytoplasmic connections were observed, which favours formation of aneuploids and polyploids. Besides various chromosomal anomalies, fertility was also significantly affected. This work envisages the possibility that although polyploidy was not achieved in some plants there is tendency to form higher ploidy levels in this species. This illustrates the potential for formation of various genetic combinations and thus novel traits. Cytomixis is also an additional source of male sterility in sunflower and thus requires intense research.
Random amplified polymorphic DNA (RAPD) and expressed sequence tags–simple sequence repeats (EST-SSR) are useful for cultivar identification. In this study, we applied a new approach using RAPD fingerprints to distinguish 34 apricot cultivars based on the optimization of RAPD by choosing 11-nucleotide (nt) primers and strict screening PCR annealing temperature. We further compared the discriminating ability of EST-SSR markers using the same number of primer pairs. The results showed that this new approach can clearly utilize and record the fingerprints generated from various RAPD primers during cultivar identification, and a cultivar identification diagram (CID) could be constructed. The CID approach can be used for efficient identification of apricot cultivars, providing information to separate groups of cultivars. The reliability and efficiency of this method was checked and verified. Five RAPD primers clearly distinguished 34 apricot cultivars, but five EST-SSR primer pairs could only identify 14 cultivars. To the best of our knowledge, this new approach is the most efficient and reliable method for identification of plant varieties by RAPD or EST-SSR markers, and will be very helpful in identification of plant cultivars, for cultivar rights protection and will also be beneficial in the nursery industry due to early identification of seedlings.
This study contributes the first genome size data for wild populations of Cynara cardunculus, the presumed progenitor of artichoke and cultivated cardoon. C-values estimated by flow cytometry are 2C = 1.98–2.14(3.03) pg for wild cardoon (10 populations), 2C = 2.10–2.11 pg for cultivated cardoon (two accessions) and 2C = 2.05 pg for artichoke (one accession). Chromosome counting (carried out for all material except the artichoke) establishes diploidy in all accessions. In order to provide a phylogenetic framework for Tunisian populations, internal transcribed spacer (ITS) region was sequenced and analysed together with previously published Cynara sequences. The wild and crop cardoons present similar karyological features and genome sizes despite strong morphological differentiation, with the single exception of a Tunisian population (from Tajerouine), which exhibits a 42–53% higher genome size. Along with Sicilian individuals, Tunisian wild C. cardunculus appear genetically closer to artichoke and cardoon than to studied wild relatives from the remaining distribution. This highlights the crucial importance of taking into consideration the North African territory in deciphering the history of C. cardunculus crop domestication.
In this study, somatic chromosome numbers of 27 Jurinea Cass. taxa (25 species and two subspecies), collected from different localities in Iran, were counted. Apart from Jurinea macrocephala DC. and J. pulchella DC. these are reported here for the first time. Except for J. eriobasis DC. with 2n = 36 and J. gedrosiaca Bornm. with 2n = 32 all the materials studied showed a somatic number of 2n = 34. Regarding the dysploidy observed in this genus two theories based on a decrease in aneuploidy and a polyploidy pillar complex are justified and discussed here.
Cytogenetic studies have been carried out on more than 750 ant taxa and are an important tool in evolutionary, taxonomic and phylogenetic studies. However, less than 10% of the species reported in the tribe Attini have been studied. The aim of the present study was to describe the chromosomes of five attine ants collected in Viçosa, Minas Gerais state, Brazil, at present unknown. The ant karyotypes reported are: Sericomyrmex sp. (2n = 50, 44m + 6sm, n = 25, 22m + 3sm); Trachymyrmex relictus (2n = 20m); Trachymyrmex sp. (2n = 22, 18m + 4sm); Apterostigma madidiense (n = 23, 7m + 10sm + 5st + 1a) and Apterostigma steigeri (2n = 22, 20m + 2sm). C-banding showed that heterochromatin was present in the centromeric region of all chromosomes of T. relictus. Future cytogenetic studies on members of the tribe Attini will provide important information to discuss chromosome evolution in this ant group.
The aim of this study was to compare seed germination percentage, seedling growth, total chlorophyll and protein content, sugar content, and root and sugar yields of sugar beet (Beta vulgaris L.) genotypes at different ploidy levels. Sugar beet seeds from cultivars “Agnessa” and “Felicita” (diploids), and lines “AD 440” and “CBM 315” (tetraploids) were obtained from the Sugar Research Institute, Etimesgut, Ankara. Seed germination percentage was recorded after 4 days, whereas seedling and root lengths were noted 4 and 14 days after the study initiation. The size of epidermal cells in length and width were determined on the upper leaf surface of 6-week-old plants. Six and 10 weeks after seed sowing, plant and root lengths, leaf length and width, plant fresh and dry weights, and total chlorophyll and protein content were measured. Data related to yield components such as sugar content, root and sugar yields were obtained from trials conducted by the Sugar Research Institute under field conditions 6 months after study initiation. In the current study, diploid genotypes showed superior responses regarding generative characteristics while tetraploids passed diploid ones vegetatively in the further stages of the development. Ten weeks after study initiation, the highest results regarding vegetative characters such as plant height, root and leaf lengths, leaf width, approximate leaf area, plant fresh and dry weights, and tissue water content were recorded from tetraploid genotypes as 35.00 cm, 43.85 cm, 18.40 cm, 9.25 cm, 170.35 cm2, 369.10 g, 77.45 g and 291.65 g, respectively while the highest total chlorophyll content and protein percentage was obtained from diploid genotypes as 1552.65 μg g–1 fresh tissue and 21.11%, respectively. The highest values of sugar content, root and sugar yields were obtained from diploid genotypes as 15.55%, 71.47 t ha–1 and 11.09 t ha–1, respectively.
A survey on chromosome counts of different sections belonging to the genus Scutellaria L. (Lamiaceae) throughout the world is presented and the relationships between chromosome data of its sections and their biogeography are also discussed here. In addition, meiotic chromosome numbers of 20 populations belonging to eight species growing in Iran, namely S. tomentosa (2n = 2x = 22), S. theobromina (2n = 2x = 22), S. araxensis (2n = 2x = 22), S. platystegia (2n = 2x = 22), S. nepetifolia (2n = 2x = 22), S. farsistanica (2n = 2x = 22), S. persica (2n = 2x = 22) and S. pinnatifida (2n = 2x = 22) were determined. With exception of S. pinatifida, all chromosome counts are reported for the first time, and are consistent with proposed base number of x = 11.
Swertia chirayita (family Gentianaceae), is a high-demand temperate pluri-annual critically endangered medicinal plant demanding immediate in situ and ex situ conservation efforts, for which understanding of its breeding behaviour, ploidy status, etc, is important. Pollination studies conducted reveal this species to be both self as well as cross compatible, as 91.60% fruit set in open pollination conditions, 87.60% under controlled xenogamy, 44.20% under geitonogamy and 34.80% under autogamy are obtained. The flower is protogynous and the stigma becomes receptive to pollen germination while still in bud condition, which would allow forced bud pollination for hybrid development. The species is genomic allotetraploid (2n = 26) with about 69% pollen stainable. Flowering and fruiting commence during August to November in its third year of growth, after which the whole plant dies.
Senna Mill. is one of the most representative genera of Caesalpinioideae, with wide geographical distribution. Some species have been cytogenetically characterized, but there is no information on population level. Therefore, the present work had the objective of characterizing and comparing chromosomal number and meiotic behavior of 39 accessions belonging to 11 species of Senna Mill. from southern Minas Gerais state, Brazil. Meiotic preparations were obtained by cell suspension technique and stained with 10% Giemsa solution. All meiotic phases were analyzed and the meiotic index was obtained. The species showed different chromosome numbers (n = 12, 13, 14, and 28). Meiotic behavior of four species is described for the first time. The chromosomal numbers reported for most species coincide with those described for populations from either Southern Brazil or from state of Pará. Intraspecific variation for chromosome number was observed in S. rugosa (G. Don) H. S. Irwin & Barneby (n = 14 and n = 28). This variation along with multivalent occurrence suggests polyploidization as an important event in the evolution of this species, as described for many others, mainly in Caesalpinioideae. Most of the analyzed species showed regular meiotic behavior, despite the occurrence of some irregularities.
To explore the composition, distribution and interrelation of the pineapple mealybugs in China, samples were collec from 14 counties of five provinces. The genetic variations of pineapple mealybugs from China, Brazil and Hawaii of USA have been analyzed. The whole ribosomal internal transcribed spacer 1 (ITS1), 5.8S and ribosomal internal transcribed spacer 2 (ITS2) were sequenced for all samples. Pink pineapple mealybug (PPM), Dysmicoccus brevipes (Cockerell) and gray pineapple mealybug (GPM), Dysmicoccus neobrevipes Beardsley are found causing damage on Ananas comosus (L.) Merr. PPM is a predominant species of mealybug on A. comosus in China. Though GPM has wider host range in China, PPM has larger distribution area than GPM. The results showed that two pineapple mealybug species belong to two different clades based on the sequences of ITS. PPM from China was found to have four haplotypes, and GPM had two haplotypes. The genetic variation of PPM is greater than that of GPM, though both of them had one predominant haplotype. One haplotype of PPM was found in samples from mainland China, and three from Hainan Island. Another haplotype of PPM was observed among the samples from Brazil and Hawaii. However, mealybugs from Wanning City of Hainan Island in China represented a different lineage that clearly diverged from other populations, which would be of a cryptic lineage or species in the pink pineapple mealybug complex. Mealybugs from Wanning City are probably native and were present long before the exotic pink pineapple mealybug was introduced in the early twentieth century. Most GPM, represented by a predominant haplotype, was widely found on sisal in plantations in south China. Other GPM, often found on sisal in urban green belt in south China, was of different haplotype from samples on sisal in plantations, probably originating from Taiwan.
Thirty-one clones of Saccharum officinarum, collected from New Guinea, were analysed and the somatic chromosome number was determined. Of the 31 clones, 29 showed 2n = 80 (typical clones), while two clones, NG 77-56 and NG 77-26, were atypical with 2n = 116 and 70 respectively. Chromosome number was determined for 62 clones of S. spontaneum, available in the world germplasm collection, through root tip mitosis. Variable numbers were identified from the same area of collection. Clones collected from north-western regions (Gujarat and Rajasthan) of India showed a majority of 2n = 80 types and 2n = 64 types, whereas 62% of clones collected from Meghalaya (north-east) showed 2n = 64. This is the first time that 2n = 80 cytotypes of S. spontaneum have been reported from the western sector of India. The clones collected from Himachal Pradesh and Uttaranchal showed lower number, e.g. 2n = 56 and 2n = 60.
Cytology of a promising oilseed woody crop, Plukenetia volubilis, was analyzed for the first time here. There are in total 11 different chromosome numbers, ranging from 2n = 50 to 2n = 86 in P. volubilis. Different numbers were found not only in different root tips but also in different cells of the same tip. Among the cells, 2.78% cells had the lowest chromosome number of 2n = 50; and 1.39% cells had the highest chromosome number of 2n = 86. The most common chromosome number is 2n = 58 and about 27.79% cells had this quantity of chromosomes. The chromosomes were extremely small in size, at less than 2 μm. Thus, analysis of chromosome morphology was impaired. Polyploidy, confirmed as the significant evolutionary trend in chromosome number within this species, is briefly discussed. This species is a problematic and polymorphic taxon and our results indicate that its polyploidy can be regarded as the reason.
The production of hybrids between napier grass (Pennisetum purpureum, 2n = 4x = 28, genomes A′A′BB) and pearl millet (P. glaucum, 2n = 2x = 14, genome AA) results in sterile triploid plants. Such sterility of the triploid hybrid creates a hurdle for napier grass breeding programs, since it prevents propagation through seeds. Fertility can be restored by means of chromosome duplication. In most cases, these duplicated Pennisetum hybrids are mixoploids. However, we do not know if there are differences between the meiotic behavior of Pennisetum hybrids between napier grass and pearl millet which were duplicated early on and those duplicated more recently. This work evaluated the meiotic behavior and the pollen viability of American and Brazilian hexaploid hybrids, which differ by about 25 years in duplication time. In all analyzed hybrids, irregularities were observed from the initial phases of meiosis to pollen grain production, independently from the time elapsed for the duplication induction. The most frequent meiotic abnormalities are related to chromosome segregation due to irregular pairing. These irregularities will directly affect the viability and the size of the pollen grains.
This is an initial report of a cytogenetic study in two economically important species of Epinephelus, namely E. bleekeri and E. coeruleopunctatus, using the G-banding technique. Chromosome numbers of the two species are 2n = 48. The differences were found to be karyotype variations, with 48 telocentric chromosomes in E. bleekeri and two submetacentric and 46 telocentric chromosomes in E. coeruleopunctatus. Statistically, there were no karyotype variations between male and female individuals of each of the species. This basic knowledge is highly important for other technologies, such as those used in hybridization programming.
In this study, 11 Vicia taxa naturally distributed in Turkey were karyologically studied. Chromosome numbers, karyotypes and idiograms of five taxa that belong to section Cracca of the genus Vicia (Vicia cracca subsp. gerardii, V. cracca subsp. atroviolacea, V. cracca subsp. stenophylla, V. canescens subsp. canescens, V. palaestina) and six taxa that belong to section Vicia (Vicia michauxii var. stenophylla, V. pannonica var. pannonica, V. hybrida, Vicia sativa subsp. nigra var. nigra, Vicia sativa subsp. nigra var. segetalis, Vicia sativa subsp. incisa var. cordata) were done. The chromosome numbers of these taxa were found as 2n = 10, 12, 14, 24. The chromosome numbers and karyotype analysis of five of these were reported for the first time and chromosome morphology of two taxa was identified for the first time. Also chromosome numbers of six taxa were verified. These results will contribute to the taxonomy of the genus Vicia which has a high diversity in Turkey.
The possible use of sterile triploid red tilapia is an interesting option for culture due to their proliferating breeding activities. The aim of the present study was to investigate and optimize the time of heat-shock treatment to prevent second polar body extrusion from the newly fertilized eggs of red tilapia, to produce a maximum number of triploid individuals. Heat-shock treatment was applied at a temperature of 41°C for a total duration of 3.5 minutes after 2, 3, 4, 4.5, 5 and 6 minutes of fertilization. The best survival rate (67.0%) and triploid percentage (89.7%) was observed for the treatment at 4 minutes after fertilization. It is thus successfully demonstrated that 4 minutes after fertilization was the most suitable timing of heat-shock treatment for second polar body retention in newly fertilized eggs of red tilapia.